Lower down on the faceplate I see an M with a crown above it and on the cylinder, M was for Monarch who were quite big into aluminium maybe still are, I think they worked in collaboration with Union, the handle could be a Monarch or it could be just a generic handle, either way I think you'll struggle, before you can even start to google search you need to know the PZ measurement, thats the distance in mm between the centre line of the handle spindle and the centre of the circular portion of the cylinder, thats the critical measurement as its fixed by the sashlock within the door, the height of the backplate no so much as you could drill extra holes higher and lower if you had to